The visual field topography of primary visual cortex (Vl) has been treated as a mapping of a single surface, the visual field. We propose instead that what is mapped is a composite of 2 (sensory) surfaces, the 2 retinas. We have developed a formal mathematical analysis that allows experimental discrimination of these two models. We propose further that the Vl map is strictly determined by the distribution of ganglion cells in the composite retina, and that the central portion of the composite retina is assembled from horizontal strips in the two retinas. To determine these mapping relationships independent of hypothesis, and to test these hypotheses, we will measure the distribution of retinal ganglion and dLGN cells, the map function from retina to Vl, and the system of ocular dominance stripes in Old World and New World monkeys. Ganglion cell density will be corrected for foveal geometry. With a combination of methods that include laser photocoagulation of a retinal pattern, cytochrome oxidase histochemistry and 2-deoxyglucose autoradiography, we will obtain in each animal the visual field map in retina and dLGN, the map function from retina to Vl, and the ocular dominance stripe system. Computation of binocular visual functions like stereo and rivalry may take advantage of the arrangement of ocular dominance stripes along the horizontal in the central portion of the visual field. Conversely, the arrangement of the ocular dominance stripes could be configured in development by circuits that promote the arrangement of the stripes along the direction of greatest disparity, that is, the horizontal. For this or some other reason, then, the overall stripe pattern may be shaped by postnatal binocular experience. To investigate the role of experience, we will examine the ocular dominance stripe pattern and the map function in newborn macaques and macaques raised with alternating monocular occlusion.